Investigations related to morphine's addictive properties are planned. Experiments concerning morphine's neuroanatomical site(s) of action(s), the neuropharmacological basis of morphine's action(s) and of morphine antagonism, the relationship of morphine analgesia to morphine addiction and the long-term consequences of in utero exposure to morphine are designed. Behavioral procedures include the study of intravenous self-administration, physical dependence produced via subcutaneous silicone reservoirs containing morphine, analgesia, active avoidance behavior and locomotor activity. Experimental brain damage, inhibitors of neurohumoral synthesis and other drugs with relatively specific modes of action will be used as tools to facilitate study of possible mechanisms of morphine's action(s). The addictive property of the amphetamines and the possible role of such agents in predisposing to morphine addiction will also be investigated.